By Justin Sink - 04/26/12 03:31 PM EDT
"There have been some days, like before Super Tuesday, I was quite fatigued, and I knew I couldn't quit. I didn't tell anybody I was tired," Romney said in an "Entertainment Tonight" interview that will air Thursday.
“You know, what happens with me is that I start to almost lose my words. I almost can't think. I can't get my words out. I start to stumble a little bit and so those things were happening and I thought, 'Uh oh, big trouble,' " she said.
Romney was diagnosed with the autoimmune disease, which affects the central nervous system, in 1998. She has spoken about her struggles with the disease on the campaign trail; during a speech Monday night, she heralded her husband for having "stood by my side" when she was diagnosed.
Supporters have often cited the disease as evidence of a challenge Romney overcame, especially in the aftermath of Democratic strategist Hilary Rosen's comments about her having "never worked a day in her life."
"I know what it’s like to struggle and to have those concerns that all mothers have,” Romney said Monday.